1. Field of the Invention
This invention relates to fasteners generally referred to in the trade as paper clips, and more particularly to a clip having a formed hinged plastic body which incorporates one or more longitudinal members of wire or other relatively flat shaped metal, for the purpose of providing additional friction holding power.
In my prior U.S. Pat. No. 3,604,067 entitled "Clip Structure" and granted Sept. 14, 1971, I disclose various modifications of a combination flat metal and plastic foam fastener. This clip structure has an exposed surface of metal and the inner side is lined with spongy plastic foam material for providing additional frictional holding power and additional protection to the papers fastened.
Such clips perform very satisfactory for fastening a relatively small number of thin paper sheets, but lack sufficient friction holding power for securely fastening a large number of sheets. In addition, such clips require painting or other protective coating of the exposed metal surface to prevent rusting. To increase friction holding power and provide full protection of the metal from rusting, I have found that the use of a flat type clip comprising a wire, strip or other longitudinal shaped metal member on or otherwise embedded in a flexible plastic body member, or positioned between two sheets or strips of such plastic, has distinct advantages and it is to that end that the present invention is directed.
2. Description of the Prior Art
Paper clips now in use are generally those of metal or plastic construction. Although most clips made of plastic provide an ample amount of flat surface for contact with the papers fastened, their friction holding power is limited and is usually less than that provided by a metal type clip.
At present, the most common type of paper clip is in the form of a wire shaped unit providing spring gripping action for holding sheets of paper together. These clips have the disadvantage that they mark, mar, indent, or distort fastened paper material. If the paper has to be duplicated, the duplicated sheet will frequently bear a mark where the clip indented the master. Moreover, this problem can be serious in computer cards, wherein an indentation on the card could result in improper processing of the card and costly machine down time. To eliminate this indentation both on paper and cards, it is a general practice to use small pieces of folded paper or card stock, placed between the wire gripper surfaces, to serve as protection pads. This is costly in terms of both material and time.
Other disadvantages of the wire clip include frequent discoloration of the paper caused by rust formed on the clip, and undesired easy detachment of the clip during stacking and filing of the fastened groups of papers. Although there have been several attempts to provide a low cost flat type clip to eliminate the deficiencies of the wire clip, the metal or plastic construction used does not provide sufficient friction holding power for good paper fastening.
Accordingly, it is an object of this invention to provide a paper clip having substantial relatively flat or planar interior surfaces which will not mar, mark, indent, or distort the paper and which will provide sufficient friction holding power to fasten separate sheets of paper, cards, or other flat material securely together.
A further object of this invention is to provide a flat type paper clip having a plastic formed hinge, such clip incorporating embedded or enclosed metal wire, strip or other relatively flat metal members, and providing the required friction holding power and which members, because of their enclosure in the plastic material, will not rust.
An additional object of this invention is to provide a paper clip of the character described, with the wire, strip, or other flat metal member removed or not present in the free end portion of one of the gripping legs, thus facilitating spreading of the gripping legs for easy threading and attachment to the papers to be fastened.
Another object of this invention is to provide a low cost machine formed flat type hinged paper clip of the character described which can be used for a variety of paper and other material fastening applications, and which can be readily fabricated in various sizes and modifications to meet needed fastening requirements.
Still another object of this invention is to provide a large type paper clip with a thumb access hole in one of the gripping legs of the clip to facilitate insertion and attachment of the papers to be fastened.
These objects are accomplished by combining the use of semi-rigid plastic and the superior friction holding power and springiness of metal in a construction that can provide weather protection for the metal and at the same time provide relatively flat or planar interior surfaces, thus eliminating the forementioned deficiencies and disadvantages of conventional paper clips such as the commonly used wire type clip.
Preferred methods of fabrication involve the use of metal wire or rod, metal strip, or other longitudinally extending relatively flat or planar metal member, laminated, embedded or otherwise enclosed in or attached or fixedly secured to plastic in sheet or roll strip form, or laminating or embedding such metal between two such forms of such flexible plastic to form a continuous strip which is then run through a machine for cutting and shaping the individual clips in accordance with the construction and modifications shown in the drawings. Other alternate methods of construction can be used such as molding, thermoforming, or spraying the plastic compound over the wire, rod, strip or other longitudinal flat metal member, in such a way as to provide a relatively flat surface on at least one side which becomes the interior sides of the legs of the finished fastener which contacts the papers to be fastened.